There are at least 76 solid elements in the periodic table. Eleven elements are gases at room temperature, while only three are liquids. Only the first 98 elements in the periodic table exist in nature.
Elements are arranged in the periodic table into 18 groups or families (vertical), and seven periods (horizontal). Elements are listed in the periodic table depending on their atomic structure. Elements in the same group or family have the same number of outermost electrons which gives them similar physical and chemical properties, while elements in each period have gradually changing chemical properties owing to the progressive rise in atomic mass from left to right.